Automotive lane deviation prevention apparatus

Abstract

An automotive lane deviation prevention apparatus includes an electronic control unit configured to be electronically connected to a yawing-motion control actuator such as braking force actuators or a steering actuator for lane deviation prevention and vehicle yawing motion control purposes. The control unit has a processor programmed for determining whether or not a host vehicle is traveling on predetermined irregularities formed on or close to either one of a left-hand side lane marking line and a right-hand side lane marking line of a driving lane. The processor is further programmed for executing vehicle yawing motion control by which the host vehicle returns to a central position of the driving lane, when the host vehicle is traveling on the predetermined irregularities.

1. An automotive lane deviation prevention apparatus comprising:
 a picture image pick-up device that captures a picture image in front of a host vehicle; 
 a lane marking line detector that detects a lane marking line based on the picture image captured by the picture image pick-up device; and 
 a processor programmed to perform the following:
 execute vehicle yawing motion control by which the host vehicle yaws away from a side position of a driving lane, when the host vehicle is traveling on predetermined irregularities formed on or close to either one of a left-hand side lane marking line and a right-hand side lane marking line of the driving lane that produce vibratory motion input into the host vehicle; 
 determine, based on the lane marking line detected, whether the host vehicle tends to deviate from the driving lane; 
 execute lane deviation prevention (LDP) control by which the host vehicle's lane deviation tendency is avoided, in presence of the host vehicle's lane-deviation tendency; 
 
 wherein the apparatus is adapted to provide the host vehicle a first desired yaw-moment controlled variable to avoid deviating from the driving lane in the event that the apparatus cannot detect a lane marking line and the vehicle is traveling on the predetermined irregularities formed on or in close proximity to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane; 
 wherein the apparatus is adapted to provide a second desired yaw-moment controlled variable to avoid deviating from the driving lane in response to the host vehicle's lane deviation tendency detected based on lane marking line detection; and 
 wherein the apparatus is adapted to correct the second desired yaw-moment controlled variable to a large value when the vehicle is traveling on the predetermined irregularities formed on or close to either one of a left-hand side lane marking line and a right-hand side lane marking line of the driving lane. 
 
   
   
     2. The automotive lane deviation prevention apparatus as claimed in  claim 1 , further comprising:
 wheel speed sensors that detect respective wheel speeds of road wheels of the host vehicle, 
 wherein the processor is further programmed for:
 (a) determining, based on signals from the wheel speed sensors, whether the host vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane. 
 
 
   
   
     3. An automotive lane deviation prevention apparatus according to  claim 1 , further including wheel speed sensors that detect respective wheel speeds of road wheels of a host vehicle;
 wherein the processor is further programmed to perform the following:
 determine that the host vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane, when at least one of the wheel speeds detected by the wheel speed sensors is fluctuating at a substantially constant time period determined based on a host vehicle speed. 
 
 
   
   
     4. An automotive lane deviation prevention apparatus according to  claim 1 , further including wheel speed sensors that detect respective wheel speeds of road wheels of the host vehicle;
 wherein the processor is further programmed to perform the following:
 determine that the host vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of a driving lane, only when either one of the left and right wheel speeds is fluctuating. 
 
 
   
   
     5. An automotive lane deviation prevention apparatus according to  claim 1 , further including a vehicle-suspension up-and-down motion sensor that detects an up-and-down motion of a suspension of the host vehicle;
 wherein the processor is further programmed to perform the following:
 determine, based on the suspension's up-and-down motion detected, whether the host vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of a driving lane. 
 
 
   
   
     6. The automotive lane deviation prevention apparatus as claimed in  claim 1 , wherein the processor is further programmed for:
 determining whether the host vehicle is traveling within an area except road-ways; and 
 inhibiting a check for the host vehicle traveling on the predetermined irregularities, when the host vehicle is traveling within the area except road-ways. 
 
   
   
     7. The automotive lane deviation prevention apparatus as claimed in  claim 1 , wherein the processor is further programmed for:
 compensating for a control gain for the LDP control in a direction that a desired yaw moment to be exerted on the host vehicle increases, when the host vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane and additionally in presence of the host vehicle's lane-deviation tendency. 
 
   
   
     8. The automotive lane deviation prevention apparatus as claimed in  claim 1 , wherein the processor is further programmed for:
 detecting a host vehicle speed, a host vehicle's yaw angle with respect to a direction of the host vehicle's driving lane, a host vehicle's lateral displacement from a central axis of the host vehicle's driving lane, and a curvature of the host vehicle's driving lane; 
 calculating a future lateral-displacement estimate based on the host vehicle speed, the yaw angle, the lateral displacement, and the curvature; and 
 determining that the host vehicle tends to deviate from the driving lane, when an absolute value of the future lateral-displacement estimate is greater than or equal to a predetermined lateral-displacement criterion. 
 
   
   
     9. The automotive lane deviation prevention apparatus as claimed in  claim 1 , wherein the processor is further programmed for:
 calculating a braking/driving force controlled variable of each of the road wheels so that a yaw moment is produced in a direction in which the host vehicle's lane-deviation tendency is avoided, in presence of the host vehicle's lane-deviation tendency; and 
 controlling braking/driving forces of the road wheels, responsively to the braking/driving force controlled variables calculated. 
 
   
   
     10. The automotive lane deviation prevention apparatus as claimed in  claim 8 , wherein the processor is further programmed for:
 calculating a braking/driving force controlled variable of each of the road wheels so that a yaw moment is produced in a direction in which the host vehicle's lane-deviation tendency is avoided, in presence of the host vehicle's lane-deviation tendency; 
 controlling braking/driving forces of the road wheels, responsively to the braking/driving force controlled variables calculated; 
 calculating, based on a difference between the future lateral-displacement estimate and the predetermined lateral-displacement criterion, a desired yaw moment to be exerted on the host vehicle; and 
 calculating, based on the desired yaw moment, the braking/driving force controlled variable of each of the road wheels. 
 
   
   
     11. The automotive lane deviation prevention apparatus as claimed in  claim 1 , wherein the processor is further programmed for:
 controlling a braking force of each of road wheels so that a yaw moment is produced in a direction in which the host vehicle returns to the central position of the driving lane, when the host vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane. 
 
   
   
     12. The automotive lane deviation prevention apparatus as claimed in  claim 11 , wherein the processor is further programmed for:
 calculating a braking/driving force controlled variable of each of the road wheels so that a predetermined constant yaw moment is produced in a direction in which the host vehicle returns to the central position of the driving lane, when the host vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane; and 
 controlling braking/driving forces of the road wheels, responsively to the braking/driving force controlled variables calculated. 
 
   
   
     13. The automotive lane deviation prevention apparatus as claimed in  claim 1 , wherein the processor is further programmed for:
 producing a steering torque in a direction in which the host vehicle returns to the central position of the driving lane, when the host vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane. 
 
   
   
     14. An automotive lane deviation prevention apparatus according to  claim 1 , further comprising:
 a yawing-motion control actuator that adjusts a yaw moment exerted on the host vehicle. 
 
   
   
     15. A method of preventing lane deviation of a host vehicle employing braking force actuators that adjust braking forces applied to respective road wheels, the method comprising:
 capturing a picture image in front of the host vehicle; 
 searching for a lane marking line based on the captured picture image; 
 detecting whether the host vehicle is traveling on predetermined irregularities formed on or close to either one of a left-hand side lane marking line and a right-hand side lane marking line of a driving lane that produce vibratory motion input into the host vehicle; 
 in the event of detection of the lane marking line, determining whether the host vehicle tends to deviate from the driving lane and executing lane deviation prevention (LDP) control by which the host vehicle's lane deviation tendency is avoided, in presence of the host vehicle's lane-deviation tendency; 
 when the host vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane that produce vibratory motion input into the host vehicle, executing vehicle yawing motion control by feedback-control of the braking forces applied to the road wheels by which the host vehicle yaws away from a side position of the driving lane; 
 in the event that there is no detection of a lane marking line and the vehicle is traveling on the predetermined irregularities formed on or in close proximity to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane, providing the vehicle a first desired yaw-moment controlled variable to avoid deviating from the driving lane; and 
 in the event of the host vehicle's lane deviation tendency detected based on lane marking line detection, providing a second desired yaw-moment controlled variable to avoid deviating from the driving lane and, if the vehicle is traveling on the predetermined irregularities formed on or close to either one of the left-hand side lane marking line and the right-hand side lane marking line of the driving lane, correcting the second desired yaw-moment controlled variable to a large value. 
 
   
   
     16. The apparatus of  claim 1 , wherein the first desired yaw-moment controlled variable and the second desired yaw-moment controlled variable correlate to a desired magnitude of yaw moment to be imparted on the vehicle to yaw the vehicle away from the side position of the driving lane. 
   
   
     17. The method of  claim 15 , wherein the first desired yaw-moment controlled variable and the second desired yaw-moment controlled variable correlate to a desired magnitude of yaw moment to be imparted on the vehicle to yaw the vehicle away from the side position of the driving lane.